Question: Rewrite ${\dfrac{9^{-3}}{9^{-7}}}$ in the form ${9^n}$.
Solution: ${ \dfrac{9^{-3}}{9^{-7}} = 9^{-3-(-7)}} $ ${ \hphantom{\dfrac{9^{-3}}{9^{-7}}} = 9^{4}} $